JPH0534516A - Color filter for display device - Google Patents

Abstract

PURPOSE:To unnecessitate the polishing of a transparent resin layer and to reduce cost by forming the resin layer obtd. by polymerizing and curing a specified compd. as a monomer on a colored layer. CONSTITUTION:A latticed light shielding pattern (black matrix) is screen-printed on a transparent glass substrate and a colored layer is formed in the light shielding pattern by screen printing with red ink, green ink and blue ink. A transparent resin layer obtd. by polymerizing and curing a compd. having a structure represented by formula I as a monomer is then formed on the colored layer. In the formula I, n is 2-4 and A is an n-valent group represented by formula II (where R is H or alkyl). For example, the transparent resin layer is formed by spin-coating the colored layer with a resin forming soln. of a monomer represented by formula III and curing the resulting resin in a nitrogen atmosphere with an area beam type electron beam irradiator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color filter for a display device.

[0002]

2. Description of the Related Art In recent years, a light receiving display element such as a liquid crystal display element has been remarkably used as a substitute for a CRT (cathode ray tube) which has been a mainstream of conventional display devices because of its thinness, lightness and low power consumption. Although showing progress, a color filter is indispensable for colorizing this display element and obtaining a display performance closer to that of a CRT.
Various materials and methods have been proposed so far.

The method for producing the colored layer constituting the color filter is roughly classified into the following. (1) Dyeing method: Dye is permeated through a polymer such as patterned gelatin to dye. (2) Slurry method: A slurry in which a pigment or a dye and a photosensitive polymer are mixed is applied and patterned by using a photolithography technique.

(3) Sol-gel method: A gel layer having fine pores is provided on a substrate to diffuse a dye. (4) Electrodeposition method: The substrate is immersed in a bath containing an electrodeposition liquid in which a pigment and an adhesive resin are dispersed, and electricity is applied to deposit the pigment and the resin on the conductive film. Then, heat treatment is performed to melt the resin and fix the pigment. (5) Printing method: An inorganic or organic pigment or dye is used to directly form a pattern on the substrate by screen, offset, gravure printing, or the like.

In these methods, except for the sol-gel method of (3), the thickness unevenness within each color or between each color is ± 0.05.
.mu.m or more occurs. In particular, the printing method (5) is a simple and inexpensive method, but there is a problem that a mountain-shaped convex portion appears in a microscopic view after fixing the ink due to the force generated when the ink separates from the plate in the printing process. . Such thickness unevenness causes problems such as insufficient contrast and gradation when used in a simple matrix type liquid crystal display device, for example.

Therefore, in the method for producing a color filter, it is desired to form a protective layer on the colored layer and polish the protective layer for the purpose of smoothing the surface.
It is proposed in Japanese Patent No. 193781, Japanese Unexamined Patent Publication No. 1-206304, and the like.

A method of manufacturing a color filter using the printing method (5) will be described with reference to FIGS.

First, a grid-like light shielding pattern (black matrix) 2 is formed on a transparent glass substrate 1 by a printing method. The light shielding pattern 2 is formed for the purpose of ensuring mutual separation of the respective color (R, G, B) patterns of the colored layer to improve the contrast and relaxing the positional deviation of the ink when forming the respective color patterns. (Fig. 2
(See (a)). Next, between the light shielding patterns 2, R, G,
Each ink of B is printed to form the colored layer 3. Due to hydrodynamic factors during printing, the surface of these inks is not flat, but has a chevron shape as schematically shown (see FIG. 2B).

Next, a resin is coated on the colored pattern 3 to form a protective layer 4 (see FIG. 2C), and then the protective layer 4 and the colored layer 3 are polished and flattened to form a color filter. (See FIG. 2 (d)).

[0010]

However, such a flattening technique is a major factor in increasing the cost because it requires a process of polishing, which is a poor productivity process. There is a problem that scratches are likely to occur.

The present invention is intended to solve the above-mentioned drawbacks of the prior art, and an object thereof is to obtain a simple and inexpensive color filter.

[0012]

The present invention comprises a transparent substrate,
It is composed of a patterned colored layer formed on a substrate and a compound (n = 2 to 4, A is an n-valent group) having a structure represented by Chemical formula 3 formed on the colored layer. The present invention provides a color filter for a display device, which comprises a transparent resin layer obtained by polymerizing and curing a monomer.

[0013]

[Chemical 3]

A is a group represented by Chemical formula 4 (provided that
The present invention provides a color filter for a display device, wherein R is hydrogen or an alkyl group).

[0015]

[Chemical 4]

In the present invention, various materials such as glass and plastic can be used as the transparent substrate according to the purpose, and are not particularly limited. From the viewpoint of application, examples of the substrate include a liquid crystal display surface, a cathode ray tube display surface, and a light receiving surface of an image pickup tube.

The patterned colored layer of the present invention may be formed by any method other than the above printing method. However, according to the printing method, since the shape pattern of the colored layer has a relatively simple shape of a substantially semicircular shape, the smoothing ability of the transparent resin layer thereon is likely to be high, which is the most preferable. Examples of the printing method include a screen printing method and an offset printing method, but the printing method is not particularly limited.

The pattern of the colored layer is not particularly limited and may be, for example, a stripe pattern, a mosaic pattern, a delta pattern or the like. Further, in order to improve the contrast, a light shielding pattern such as a black matrix may be formed between the patterns, and the black matrix may be formed not only by the printing method but also by the spin coating method or the like. The printing method is most preferable for the same reason.

In the present invention, the transparent resin layer formed on the colored layer is a compound having a structure represented by Chemical formula 3 (n =
2 to 4, A is a monomer obtained by polymerizing and curing a monomer composed of an n-valent group).

As an example of such a transparent resin layer, a monomer composed of a compound having a structure represented by Chemical formula 5 is added to a cyclobutene moiety in the structure represented by Chemical formula 5 and a double bond of carbon. It can be obtained by a so-called Diels-Alder reaction with a part. In Chemical formula 5, R represents hydrogen or an alkyl group, and each R may be different. Further, the chemical compound 6 is a compound in which two monomers of the chemical compound 5 are polymerized.

[0021]

[Chemical 5]

[0022]

[Chemical 6]

Polymerization and curing of the resin of the present invention is not limited to a thermal reaction using an ordinary oven, a hot plate, a far infrared heater or the like, and may be a reaction using an electron beam.

The solvent is not particularly limited, but mesitylene, xylene and the like can be preferably used, and mesitylene is used to bring out the ability of smoothing unevenness of the base, which is the most characteristic feature of bringing the effect of the present invention to a high level. Most preferably.

[0025]

The transparent resin layer for a color filter of the present invention has a high ability to smooth the unevenness of the underlying colored layer when the resin used for the transparent resin layer is cured. Therefore, the surface of the color filter is polished in a later step. There is almost no need to physically smooth it.

Although the mechanism for smoothing the resin is not always clear, it is considered that the resin itself has a fluidity during curing even after the solvent is evaporated, so that a high smoothing ability is brought about. Since the polishing step can be omitted, it is possible to achieve effects such as a reduction in the manufacturing time of the color filter, a reduction in cost, and an improvement in quality due to elimination of the cause of scratches.

[0027]

【Example】

Embodiments Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a method of manufacturing a color filter according to the present invention.
This will be described with reference to (a) to (c).

First, a grid-shaped light shielding pattern (black matrix) 2 was screen-printed on a transparent glass substrate 1. The light shielding pattern 2 is formed for the purpose of ensuring mutual separation of the color filter patterns to improve the contrast and mitigating ink misalignment when forming the color filter patterns (FIG. 1).
(A)). Next, the R, G, and B inks were screen-printed between the light shielding patterns 2 to form the colored layers 3. Due to the hydrodynamic factors during printing, the surface of these inks is not flat, but has a chevron shape as schematically shown (FIG. 1B).

Next, on the colored layer 3, a resin-forming liquid having a structure shown in Chemical formula 5 and consisting of a monomer having a methyl group as R is spin-coated and applied so as to have a film thickness of 3 μm after curing. did. After that, using an area beam type electron beam irradiation device, an acceleration voltage of 150 kV, an electron flow of 9.8 mA,
It was cured under a nitrogen atmosphere at an irradiation dose of 600 Mrad (FIG. 1 (c)).

(Comparative Example) A comparative example will be described as a method for producing a color filter when an acrylic resin, which is a resin generally used in the past, is used as the coating layer on the colored layer.

First, in the same manner as in the above example, a colored layer was formed by screen printing on a transparent glass substrate. Then
An acrylic resin (Optomer SS7235 manufactured by Nippon Synthetic Rubber Co., Ltd.) was spin-coated on the colored layer so that the film thickness after curing was 3 μm. Then, it was hardened by heating in an oven at 225 ° C. for 1 hour.

[0032]

EFFECTS OF THE INVENTION With respect to the color filters manufactured by the methods of the above Examples and Comparative Examples, the surface roughness before and after the formation of the coating layer on the colored layer was examined using a surface roughness meter, and the smoothness defined by the following formula was obtained. The smoothing property was evaluated by obtaining the conversion rate δ. The results are shown in Table 1 and FIGS. 3 (a) to 3 (c).
(A) shows the surface roughness before forming the transparent resin layer, and (b) and (c) respectively show the surface roughness on the colored layer having the surface roughness as shown in (a) according to the method of Examples and Comparative Examples. It is a figure showing surface roughness when a transparent resin layer is formed.

Smoothing rate δ = (1−a / b) × 100 (%) (In the formula, a represents a step on the surface after forming the coat layer, and b represents a step before forming.)

[0034]

[Table 1]

As is clear from Table 1 and FIG. 3, it can be seen that the method of Example can significantly improve the unevenness of the surface of the colored layer as compared with the method of Comparative Example.

In the method of the comparative example, there is a surface step difference of ± 0.3 μm after the formation of the coat layer, and if it is used as it is, for example, when it is used for a simple matrix type liquid crystal display device, sufficient contrast and gradation cannot be obtained. Problems such as occur. Therefore, it is necessary to polish the coat layer to physically smooth the surface.

On the other hand, in the method of the embodiment, a surface having a smoothness of at most ± 0.05 μm was formed after forming the coat layer. With this precision, uniform and high-quality display can be achieved without variations in V _th and contrast for each color of the liquid crystal display device. Therefore, since the polishing step is unnecessary, the manufacturing time of the color filter can be shortened, the cost can be reduced, and the quality can be improved by eliminating the cause of the scratches.

Further, by using the printing method for forming the colored layer, there is an advantage that it can be manufactured easily and at a low cost, but the drawback of the printing method that the surface has a mountain shape and a large step is solved by the method of the embodiment. As a result, the cost of the color filter as a whole can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a manufacturing process of a color filter of the present invention.

FIG. 2 is a diagram showing a manufacturing process of a conventional color filter.

FIG. 3 is a diagram showing surface irregularities in Examples and Comparative Examples.

[Explanation of symbols]

1 transparent glass substrate 2 Light shielding pattern 3 colored layers 4 Transparent resin layer

Claims (3)

[Claims] 1. A transparent substrate, a patterned colored layer provided on the substrate, and a compound having a structure represented by Chemical formula 1 provided on the colored layer (n = 2 to 4, A is a color filter for a display device, comprising a transparent resin layer obtained by polymerizing and curing a monomer composed of an n-valent group). [Chemical 1] 2. A color filter for a display device according to claim 1, wherein the formula A is a group represented by Chemical formula 2 (wherein R is hydrogen or an alkyl group). [Chemical 2] 3. The color filter for a display device according to claim 1, wherein the colored layer is provided on the substrate by printing.